Tools – Wrench – screwdriver – or driver therefor – Machine
Reexamination Certificate
1999-07-08
2001-05-01
Eley, Timothy V. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Machine
C081S057330
Reexamination Certificate
active
06223629
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates to power tongs typically used in the oil and gas industry to make up and break apart threaded joints on pipe, casing, and similar tubular members.
Power tongs have been used for many years and are generally employed in the oil and gas industry to grip and rotate tubular members, such as tubular. The tubular members are gripped with high compressive forces while applying a high degree of torque to break apart or tighten threaded tubular member connections. In most cases, power tong designs employ a cam mechanism for converting a portion of the torque into a gripping (compressive) force normal to the tubular member. This conversion is often accomplished using a power-driven ring gear having an interior cam surface. As the ring gear rotates, cam follower (roller) on a jaw member rides upon the cam surface, causing the follower (and thus the jaw member) to move into contact with the tubular member. U.S. Pat. No. 4,404,876 discloses such an arrangement.
Most current power tong designs include a ring gear cam with an open slot or throat (“open-throat power tongs”), through which the tubular member passes to position the jaw members around the tubular member. However, some tong designs employ a ring gear cam that has no open throat and is thus a solid circular member. This solid circular ring gear design is generally referred to as a closed-head power tong.
When the drilling environment allows the use of a derrick or similar overhead structure from which a power tong may be suspended, an openthroat power tong is often a more efficient tool. Open-throat power tongs easily disengage and/or retract from the tubular member when the operator desires to raise, lower, or otherwise manipulate the tubular member.
On the other hand, a closed-head power tong is more difficult to retract from the tubular member because it has a closed throat and must pass over the end of a tubular member. However, there are common drilling environments where there is no structure from which an open-throat power tong may be suspended and insufficient workspace to engage and retract open-throat power tongs. In such environments, a closed-head power tong may be the only practical alternative. Closed-head power tongs are highly useful during operations where snubbing units are employed. Typically, closed-head power tongs are positioned over the drill string with the individual tubular members forming the drill string extending through a center aperture in the closed-head power tong. A tubular member is moved vertically through the center aperture until the threaded joints for connecting adjacent tubular members are in position to be made up (screwed together) or broken out (unscrewed).
To increase efficiency, as many successive tubular member connections as possible are made-up or broken out without interruption, i.e. having to move the center aperture of the tong out of alignment with the drill string. However, the drill string may include a down hole tool or other device that has a diameter greater than the diameter of the center aperture of the closed-head power tong. In these situations, the prior art closed-head power tongs typically require that the drill string be broken and any tubular positioned in the center aperture at that point be removed therefrom. The closed-head power tongs are then removed from alignment with the drill string, and the oversized tool is removed from the drill string or re-positioned vertically along the drill string above or below the power tong such that it is not required to pass through the power tong. The closed-head power tong can then be re-aligned with the drill string. To re-establish the connection of the drill string through the center aperture, the unconnected tubular joint must be positioned above or below the center aperture to reconnect to a continuous length of drill string.
What is need in the art is a closed-head power tong design which allows the center aperture to be readily increased in diameter without the necessity of removing the drill string from the center aperture. The closed-head power tong design should provide for center aperture enlargement with a minimum lost time and with such simplicity that unskilled workers could perform the task.
OBJECTS AND SUMMARY OF THE INVENTION
With the aforementioned considerations in mind, it is therefore an object of this invention to provide a power tong assembly used in connection with a conventional snubbing unit.
It is a further object of the present invention to provide a closed head power tong that is adapted to increase the gripping aperture therein to allow passage of objects having a diameter larger than the normal gripping aperture.
It is a further object of the present invention to provide a closed head power tong that may be quickly and efficiently operated without the necessity of removing the power tong from alignment with the drill string.
The invention herein comprises a closed-head power tong having a power tong body. The tong body has a ring gear positioned within the body, and the ring gear comprises at least one cam surface. The tong body also has a cage plate assembly comprising at least two mating inserts and a jaw aperture formed in at least one of the mating inserts.
The invention may also comprise a power tong body having a ring gear positioned within the body wherein the ring gear has at least one cam surface. A cage plate assembly is removably positioned at least partially within the body and configured to have a gripping aperture therein. The gripping aperture has first dimension and the cage plate assembly is adapted to increase the gripping aperture to a second dimension sufficiently sized to allow passage of an object having a dimension larger than the first dimension.
A method of making up or breaking one or more section of tubular members using the closed head power tong invention is also disclosed herein. The method comprises the steps of (a) removing the cage plate assembly from the power tong body, thereby increasing the diameter of the gripping aperture to allow passage of a tool; and (b) passing the tool through the power tong body a sufficient distance so that the cage plate assembly may be repositioned within the power tong body.
REFERENCES:
patent: 1811666 (1931-06-01), Foster
patent: 4372026 (1983-02-01), Mosing
patent: 4404876 (1983-09-01), Eckel
patent: 4572036 (1986-02-01), Renfro
patent: 4649777 (1987-03-01), Buck
patent: 4836064 (1989-06-01), Slator
patent: 4869137 (1989-09-01), Slator
patent: 4979356 (1990-12-01), Vatne
patent: 5044232 (1991-09-01), Schulze-Beckinghausen
patent: 5271298 (1993-12-01), Gazel-Anthoine
patent: 5291808 (1994-03-01), Buck
patent: 5819605 (1998-10-01), Buck et al.
patent: 5845549 (1998-12-01), Bouligny
Eley Timothy V.
Nguyen Dung Van
Roy Kiesel & Tucker
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